System for compensating for differences of potentials.



H, M BASCOW.

SYSTEM FOR COPWENSATWG FOR DIFFERENCES 0F POTENNALS.

APPUCATION mm MAX 1. m1.

H. M. BASCOM.

SYSTEM FOR COMPENSATING FOR DIFFERENCES OF POTENTIALS.

APPLICATION FILED MAY I7. l9l7- 4 SHEETSSHEET 2.

IHII IH H Patented Dec. 17, 1918.

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IN VEN TOR. fienryM Bawwm BY TAM/w 4/1 I ATTORNEYS.

H. M. BASCUM.

ATING FOR ommmcas OF POTENTIALS.

APPLICATION FILED SYSTEM FOR COMPENS MAYIY, ISM".

Patonmd D4 0. 17, 1918.

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SYSTEM FOR COMPENSATING FOR DIFFERENCES 0F POTENTIALS.

7 APPLICATION HLED MAY I7, I91]. 1,287,831,

Patented Dec.17, 1918.

4 SHEETSSHEET 4.

PATENT @FFIQE HENRY M. BASCOM, OF BROOKLYN, NEW YORK, ASSIGN'OR'TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

SYSTEM FOR COMPENSATING FOR DIFFERENCES OF POTENTIALS.

Application filed may 17, 1917.

To all whom it may concern:

Be it known that I, HENRY M. BASCOM, residing at Brooklyn, in the county of Kings and State of New York, have invented certain Improvements in Systems for Compensating for Differences of Potentials, of which the following is a specification.

In a number of types of signaling circuits, as those employed for duplex telegraphy or for the common battery operation of signals over phantomed telephone circuits, the action of the relays or other signal controlling devices depends upon a balance of electrical or magnetic forces, one of the balanced forces being supplied over a common return, which may consist of a ground or a metallic conductor, the separated terminals of which are subjected to diflerences of potential, while the other force is produced locally and is therefore not afi'ected by the previously mentioned potential differences. In absence of means for preventing this, the How of current through one of the two circuits may so unbalance the devices that they fail to operate properly. To provide such a compensating means is the object of my invention.

To illustrate the invention, I have chosen from the several systems in which it may be incorporated, one for controlling from a central station battery signaling lamps associated with phantomed telephone circuits, a system of this character being shown d1agrammatically in the accompanying drawings, Figure 1 representing one central station and the corresponding portion of the circuits, and Fig. 2 another central station with its portion of the circuits.

Fig. 1 and Fig. 1 illustrate a slightly different embodiment of the same invention.

Between the central stations A and A extend two physical trunk circuits, including respectively the conductors L, L and L L terminating at jacks J and J for the cooperation with the plugs P and P of the usual cord circuits C and C. The terminal conductors'of the phantom circuit appear at Z, these also terminating at Jacks J and J. In accordance with the customary ractice each trunk at the central station has the respective lamp signals 0, O, by which is indicated the connection with the associated jack of the plug of the distant Specification of Letters Patent.

Patented Dec. 17, 1918.

Serial No. 169,223.

to the usual practice, the relays R R possess two windings 10, 11, and 10, 11, which are differential and at times have equal operating currents passing through them oppositely to neutralize one anothers action. All these windings 10 and 10 are supplied with current locally at the stations A and A from common batteries B and B, respectively, while windings 11 and 11 receive their current over the trunk conductors, the ends of these conductors being grounded at G and G to complete the circuits. The difference of ground potential between two stations frequently becomes suiiiciently great to cause a resultant flow of current through the line, which disturbs the balance of. the differential windings, and the lamps controlled by the relays are incorrectly lighted or extinguished. To prevent this, I provide each of the relays R R with a third winding 12 or 12 equal and opposite in eiiect to the windings 11, 11, and through which are permitted to flow any earth currents created by the same potentials as are applied to said windings 11, 11'. For the operation of the signaling relays, three conductors of the two physical circuits are employed, as L, L and L thus permitting independent control of the signals for each of the three telephone circuits. The conductor, L, remaining I utilize as a compensating conductor and to it join the windings 12, 12 of the relays R and R of both physical circuits and the phantom circuit, this being in the present instance in series. The terminals of this compensating conductor are grounded at G at station A and G at station A, these grounding points being so located with respect to the grounds G and G of the signaling circuits that they are at the same potentials. It will be noted that at each station there is included in the compensating circuit three of the windings 12 or 12, while corresponding to these in each signaling circuit there cuit of lamp U cuit with each of the windings 11 or 11 a resistance r twice that of the windings 12, 12. Furthermore, to maintain the balance between windings 10 and 11 and 10 and 11, resistances o equal to 7' are placed in the local circuits. These latter are in addition to resistances 1*, used to equalize the resistance of the local circuits through windings 10 and 10 and the trunk circuitsthrough windings 11 and 11. and functions of tl'ie'elenients not previously described will be brought out in the following statement or operation.

it being assumed that the operator at station A trunks a call to station. A over the line L, L upon the insertion of the plug it of her cord C in the jack J of this trunk, relay R is energized from battery B over the sleeve strand of the cord, sleeve conjack, and local conducv tacts oi" the plug and tor 18 of the trunk. At its contact 14. relay l connects battery to a point it between the windings l0 and 11 of relay from this, point currentdows to ground locally through the winding 10 and resistances a" and 9' and also over the trunk to station A, the latter circuit including winding 11 of rela T5 resistance r, winding 15 or the retan ation coil l, trunk conductor L, windings 15 of retardation coil l, resistance r station A, winding 11 of relay R conductor l6 and contact 17 of relay E to ground. Because of the di'i erential character or windings 10 and 11 relay does not attract its armature the currents flowing therethrough are equal. So far as operating currents are concerned, this is provided for by substantial equality of resistance oi the circuits. of'windings 10 and ll. The widely separated grounding points G and G may however, at the time be under the influence of substantial differences of ground potential and whatever current from this source circulates in the windings ill and ii oi relays R and R respectively, passes equally over the compensating conductor L and oppositely through the windings i2 and 12. The effect of ground potential upon relays and R is therefore neutralized and their proper operation is not interfered with. Relay E is energized and at contact l8'completes the cirthrough the resting con tacts 19 and 20 of relays l and R respectively. The operator at station A observing this signal inserts the plug i of her cord circuit C in the jack J of the trunk L, L, energizing relay R through the sleeve circuit battery '13". This e tinguishes the lamp '9 by opening contact 19. At its contact 21 a pat l for current through relay'il is formed by way oi its 22 and contact 18 of relay 2i and at con- The novel relations.

that the answering supervisory relay lit in the cord circuit C may operate. Relay ll also transfers the connection of conductor 16 from ground contact 17 to battery contact 22. The batteries B and B of stations A and A now oppose one another and consequently the windings 11, 11' of relays R and R receive no operating current, the equalization of efiect with respect to earth currents being maintained by the windings 12, 12 of these relay s. Current still tlows drorn battery B through winding 10 of relay it and winding 10 of relay R now has current from battery B by way of contact 22, conductor 16 and resistances r and 7*. Relay R therefore remains operated and relay R attracts its armature. There is now a circuit for relay li by way of contact 23 of relay it break contact 2% of relay and front contact 25 of relay R The consequent operation of relay R causes it to lock itseli through contact 26 and to close at contact 27 a bridge oi condenser c to energize the calling supervisory relay E in the cord circuit C. This completes the signaling operations incident to originating a connection.

It when disconnection is desired the oporator at-A withdraws the plug P from the jack 5 thecircuit of relay ll is severed at the sleeve contacts of the plug and jaclr. lileleasing it removes battery B from the windings l0 and 11' oi relay R at con tact 22 and unites ground thereto at c0ntact 17. Though the winding 10' no longer receives current there is a circuit from battery B at station A over the trunk for the windings ll and 11' of relays R and R As previously pointed out, compensating earth currents flow in the windings l2 and i to release the supervisory relay R in the cord circuit C. Upon the consequent lighting of the calling supervisory lamp 0 the operator at station A removes the plug P from jaclr J and the release of relay R opens contact 14. This cuts 05 battery from the circuit of relays it and R the breaking of contact 18 of the latter'deenergizing relay The system is now restored to its normal condition.

it will be obvious that instead or the ground return above described a common metallic return conductor X might be employed as illustrated in Fins. l and 1". which are in other respects identical with i 2 above described therefore require no further detailed description. In this modified arrangement, the battery'for signaling between stations A and A would be independent from that used to operate local relays and lamps. In this case the differences of potential for which it would be necessary to compensate are due to the drop in potential between the stations through the resistance of the conductor X.

I claim as my invention:

1. In a system for compensating for differences of potential, signaling stations, a plurality of signaling conductors connecting the stations, a compensating. conductor connected to the signaling. conductors at the stations, and a relay at each station provided with a winding in its respective signaling conductor, there being windings for all the relays included in the compensating conductor and being equal and opposite in effeet to the windings in the signaling conductors.

2. The combination with separated stations, a plurality of line circuits connecting the stations, a relay at each station for each line circuit, an operating circuit for the relays of each line, said operating circuit including a conductor of a line circuit, and a compensating circuit for the relays including a line conductor different from those utilized for the signaling circuits.

3. In a system for compensating for differences of potential, signaling stations, a plurality of signaling conductors connecting the stations, a compensating conductor connected to the signaling conductors at the stations, a relay at each station provided with a winding in its respective signaling conductor, there being windings for all the relays included in the compensating conductor and being equal and opposite'in effeet to the windings in the signaling conductors, and a resistance included in each signaling conductor corresponding to the resistance of the other compensating windings than those associated with its relays.

4. In a system .for compensating for ground potentials, a plurality of grounded signaling circuits, circuit exposed to substantially the same difi'erences of ground potential as the signaling circuits, and electromagnetic signal controlling devices each having a plurality of windings, two of which are inductively opposing one of the two being in one of said signaling circuits, there being associated I with each electromagnetic device another winding included in the compensating circuit and producing an efiect opposite to that in the signaling circuit.

5. The combination with a signaling circuit having separated; ground connections subject to differences of ground potential. a compensating circuit grounded at points subject to said dificrencs of ground potena grounded compensating tial, and a signal controlling relay providedwith differential windings one of which is in the signaling circuit and with an oppositely acting winding in the compensating circuit.

6. The combination with signaling stations, of a signaling conductor connecting the stations, a common return therefor, a circuit local to one of the stations, a compensating conductor extending between the stations and being connected to the common return, and an electromagnetic device having windings in the signaling conductor, in the local circuit and in the compensating conductor.

7. The combination with signaling stations, of a signaling conductor connecting the stations, ground connections for the signaling conductor at each station, a circuit local to one of the stations, a compensating conductor extending between the stations and being provided with ground connections thereat, and an electromagnetic device hav-' ing windings'in the signaling conductor, in the local circuit and in the compensating conductor, the first two windings being differential and that of the compensating con-' ductor being opposite in its efiect to that in the signalin conductor.

8. In a te ephone System,.central stations, a trunk line between the stations subject to difl'erences of potential, signals at the stations, a relay at each station acting to control the signals, an operating circuit for the relays including a conductor of the trunk, and a compensating circuit common to said relays, both of said circuits being subjected to like potentials at both stations.

9. In a telephone system, central stations, a trunk line between the stations subject to difi'erences of potential,- signals at the stations, a relay controlling the signals, an operating circuit for the relay including a conductor of the trunk, and a compensating circuit for the relay including another conductor of the trunk, both of said conductors being subjected to like potentials at both stations.

10. In atelephone system, central stations,

a trunk line connecting the stations subject to difierences of potential, signals situated at the stations, a relay at each station actin to control the signals, an operating circuit for the relays including a, conductor of-the trunk, and a compensating circuit for the relays including a trunk conductor, both of said circuits bei g subjected to ground potentials at both stations.

11. In a telephone system, central stations,

'a trunk line connecting the stations subject to diflerences of potential, signals at the stations, a relay at each station having a plurality of windings and actin to control the signals, a circuit through t e windings of said relays including a trunk conductor, and

e compensating circuis fier other eqnei enci cppcsice windin s cf the relays, said circuit also including e trunk ccnductcr.

12. The-ceinbinetien with separated. stetions, of a plurality cf line circuits connecting the stations, a signs fer each line circuit, a relay contrciiing each signal, an operating circuit for, the reiay of each line, said operating circuit inciuriing e, ccnductcr of a line circuit and a ccinmcn return, and a compenseting circuit for she relays inciuding a line ccnductcr (ii erent irczn that utilized for the signaling; circuit and the common re- 13" corn pnene circuits and s pnentem circuit formed ierei rcm er signals associated with each circuit, 8 reiey controlling the signals or? each circuit separate circuics for independently geverning the relays, said circuits being furnished by three or the four cenductcrs cf the physical circuits and grcnnii ccnnecticns therefor, and a common ecmpensaeing circuit for all the relays furnished by the fourth conductor ground; ccnnectiens ciiereicr.

In testimony wiiereci I have signed my name be his specification *chis sevenin (icy of May, 

